The central bank in the United States is already nationalized. Since the banking acts passed in the 1930's it's been a de facto, pseudo independent branch of the U.S. Treasury Dept. This can be proven by examination of the consolidated Central Bank and Treasury Accounts.
The U.S. Central Bank has a hybrid structure in which private banks have input into decision making, but the board of governors, on which private banks have only very minor representation, along with the FOMC, a sub unit of the BOG, thoroughly dominate decision making as to the wholesale price of the U.S. dollar, i.e., the Fed Funds rate. Bank reserves and the Fed balance sheet respond accordingly to the decisions of the FOMC and BOG.
A gold standard is no longer tenable or practical. Beginning in the late 1960s it became increasingly difficult for the the U.S. central bank to control the price of gold. This is why the gold standard failed in 1971. The U.S. central bank was redeeming in gold other central bank dollar assets for $35/Oz. While elsewhere gold was selling for $40/Oz. Obviously an unsustainable situation.
In 1944, Keynes had predicted the gold standard would eventually fail. He unsuccessfully advocated for adoption of a special reserve currency based on a basket of national currencies. If the U.S. Fed eventually loses control of the unit buying power of the U.S. dollar, and they likely will, then that is where we in the U.S. and the world is headed. We may be headed in that direction regardless, for political reasons.
